1. Field of the Invention
The present invention relates to a device for the arrangement of a roller of a forms printing device in a copying or printing machine, the roller receiving a master copy, and more particularly to such an arrangement in which the forms printing device contains a lamp tube seated on the housing of the device and the roller can be slipped onto and locked to the lamp tube.
2. Description of the Prior Art
Non-mechanical printers which function according to the electrostatic principle are well known in the art. Such printers generate either electrophotographic or electrographic charge images of the characters to be printed on a recording medium. The recording medium can be the paper per se or an intermediate carrier. The charge images on the recording medium are developed with the assistance of a toner. If the paper to be printed is itself employed as the recording medium, then the fixing installation by means of which the developed charge image is fixed on the paper, for example with heat, follows immediately upon the development installation. If, however, in non-mechanical printing, an intermediate carrier is employed, for example, a xerographic drum, then the developed charge images are transferred onto the paper to be printed and are only subsequently fixed.
In such electrostatic printers, there is a desire to provide the charge images of forms to be printed at the point in time of the generation of the charge images of the characters to be printed on the recording medium. It is therefore necessary that the generation of the charge images be independent of the character generation of the characters to be printed on the recording medium.
As an example of such a forms printing device is this structure set forth in the German published application No. 2,616,137. In this disclosure, a negative of the form to be printed is applied to a transparent roller. This negative is designated as the master copy in the following. A light source, for example a flourescent tube, is arranged within the transparent roller. This light source illuminates the roller from the interior and, therefore, also illuminates the master copy. The light proceeding from the master copy is imaged on the recording medium by sections by means of an aperture. The roller is moved in synchronism with the recording medium. Since forms of different size must be imaged on the recording medium, rollers having different circumferences are also required. This means that the rollers must be arranged in the printing device in such a manner that they can be easily interchanged.